1. Field of the Invention
The present invention relates generally to air conditioning systems which include a hybrid compressor, and vehicles comprising such air conditioning systems. In particular, the present invention is directed towards vehicles and air conditioning systems, in which a limit for an amount of electrical power, which an electric drive source of the hybrid compressor may consume, varies during operation of the air conditioning system.
2. Description of Related Art
Known hybrid vehicles include a first drive source, e.g., an engine, and a known air conditioning system. Such known air conditioning systems, such as the air conditioning system described in U.S. Pat. No. 5,867,996, include a hybrid compressor and a refrigeration system. The hybrid compressor includes a second drive source, e.g., an electric motor, and an electrical power supply, e.g., a battery, for the second drive source. The hybrid compressor may be driven by the first drive source or the second drive source, or both. Specifically, the first drive source drives the hybrid compressor when the first drive source is engaged, and the second drive source drives the hybrid compressor when the first drive source is disengaged. As such, whether the first drive source or the second drive source drives the hybrid compressor depends on whether the first drive source is engaged or disengaged.
In such known air conditioning systems, when the second drive source drives the hybrid compressor, the compressor consumes electrical power. Moreover, a limit for the amount of electrical power which the compressor may consume is preselected, and the rotational speed of the compressor is controlled, such that the amount of electrical power consumed by the compressor is less than or equal to the preselected amount of electrical power. Nevertheless, if the preselected amount of electrical power is less than an optimum amount of electrical power, the air conditioning system may be unable to deliver sufficiently cooled air or sufficiently heated air to an interior of the vehicle when a load of the refrigeration system is greater than a predetermined load. Similarly, if the preselected amount of electrical power is greater than the optimum amount of electrical power, the ability of the second drive source to drive the compressor for extended periods of time is reduced.
Therefore, a need has arisen for air conditioning systems for vehicles which overcome these and other shortcomings of the related art. A technical advantage of the present invention is that a limit for the amount of electrical power which the second drive source of the hybrid compressor may consume varies during an operation of the air conditioning system. Specifically, when the amount of electrical power consumed by the second drive source is greater than a first limit for the amount of electrical power which the second drive source may consume, the air conditioning system may (1) decrease the rotational speed of the second drive source until the amount of electrical power consumed by the second drive source is less than or equal to the first limit, and (2) increase the limit for the amount of electrical power which the second drive source of the hybrid compressor may consume from the first limit to a second limit. Whether the air conditioning system merely decreases the rotational speed of the second drive source, or decreases the rotational speed of the second drive source and increases the first limit to the second limit, may depend on whether predetermined conditions are satisfied. Satisfaction of the predetermined conditions may indicate that it is desirable to increase the first limit to the second limit, or that the first limit may increase to the second limit without substantial adverse affects to the ability of the second drive source to drive the hybrid compressor or the vehicle, or both.
According to an embodiment of the present invention, an air conditioning system for a vehicle comprising a first drive source, comprises at least one compressor. The at least one compressor comprises a second drive source, and the at least one compressor is driven by the first drive source or the second drive source, or a combination thereof. The second drive source comprises an electrical power supply. The air conditioning system also comprises means for selecting at least one of the first rive source and the second drive source for driving the at least one compressor, e.g., a controller, and means for detecting an amount of electrical power consumed by the second drive source, e.g., a voltmeter or an amp meter. Moreover, the air conditioning system comprises means for controlling a rotational speed of the second drive source. Specifically, when at least one predetermined condition is satisfied and an amount of electrical power consumed by the second drive source is greater than a first limit of the amount of electrical power which the second drive source may consume, the first limit increases to a second limit. For example, the air conditioning system also may comprises a refrigeration system, and the at least one predetermined condition may be satisfied when a load of the refrigeration system is greater than a predetermined load. The at least one predetermined condition also may be satisfied when an amount of electric power stored in the electric power supply is greater than or equal to a predetermined amount of stored electric power. Moreover, the at least one predetermined condition may be satisfied when an amount of electrical power consumed by at least one element of the air conditioning system other than the at least one compressor is less than a predetermined amount of consumed electrical power.
According to another embodiment of the present invention, a vehicle comprises a first drive source and an air conditioning system, and the air conditioning system comprises at least one compressor. The at least one compressor comprises a second drive source, and the at least one compressor is driven by the first drive source or the second drive source, or a combination thereof. The second drive source comprises an electrical power supply. The air conditioning system also comprises means for selecting at least one of the first drive source and the second drive source for driving the at least one compressor, e.g., a controller, and means for detecting an amount of electrical power consumed by the second drive source, e.g., a voltmeter or an amp meter. Moreover, the air conditioning system comprises means for controlling a rotational speed of the second drive source. Specifically, when at least one predetermined condition is satisfied and an amount of electrical power consumed by the second drive source is greater than a first limit of the amount of electrical power which the second drive source may consume, the first limit increases to a second limit.
Other objects, features, and advantages will be apparent to persons of ordinary skill in the art from the following detailed description of the invention and the accompanying drawing.